LTE supports high-speed train scenarios with a maximum speed of 350 km/h. In order to ensure quality of service for mobile terminals in different mobility states, LTE is not only optimized accordingly in the network structure, but also designed with a corresponding mechanism which enables a mobile terminal to adaptively optimize the parameter configuration to comply with the requirements in different scenarios according to its current mobility state.
The above mechanism is mobility state estimation (MSE) for a mobile terminal in LTE. Mobility state estimation for a mobile terminal in LTE is based on the count of number of times of cell reselection. In a conventional homogeneous network, the above mobility state estimation based on the count of number of times of cell reselection can provide a relatively accurate estimation of the mobility state of the mobile terminal. However, with the introduction of heterogeneous network, the randomness of small cell deployment positions and the nonuniformity of coverages will greatly affect the accuracy of the above mobility state estimation based on the count of number of times of cell reselection.
In a heterogeneous network, a macro cell is deployed with various types of Low Power Nodes (LPNs) such as micro base stations, pico base stations, femtocell base stations and remote radio units. In addition, due to the differences in transmission power between the various types of small cells, they have different coverages. The conventional mobility state estimation is under a fundamental assumption that the cells in the network have substantially the same coverage. However, in a heterogeneous network, due to the presence of the various types of low power nodes, the above assumption does not stand. In addition, a mobile terminal in a heterogeneous network sees a significantly increase in the number of times of cell switching or reselection, which tends to give the illusion that the mobile terminal is moving at a high speed. Moreover, the lack of accuracy in mobility state estimation will further affect on those mechanisms relating to mobility state estimation, such as speed scale factor, thus failing to meet basic requirements of mobility of mobile terminals in a heterogeneous network.
It is therefore desirable to provide a device and a method in a wireless communication system, to ensure the stability of mobility performance of a mobile terminal in a heterogeneous network, so as to provide the user with a seamless and stable network coverage.